Effect of carbonate ion concentration and irradiance on calcification in planktonic foraminifera
- 1LSCE/IPSL, laboratoire CEA/CNRS/UVSQ, LSCE-Vallée, Bât. 12, avenue de la Terrasse, 91198 Gif-sur-Yvette CEDEX, France
- 2Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
- 3INSU-CNRS, Laboratoire d'Océanographie de Villefranche-sur-mer, B.P. 28, 06234 Villefranche-sur-mer Cedex, France
- 4UPMC University of Paris 06, Observatoire Océanologique de Villefranche-sur-mer, 06230 Villefranche-sur-mer, France
- *currently at: DTU Aqua, Technical University of Denmark, Kavalergården 6, 2920 Charlottenlund, Denmark
Abstract. The effect of carbonate ion concentration ([CO32−]) on calcification rates estimated from shell size and weight was investigated in the planktonic foraminifera Orbulina universa and Globigerinoides sacculifer. Experiments on G. sacculifer were conducted under two irradiance levels (35 and 335 μmol photons m−2 s−1). Calcification was ca. 30% lower under low light than under high light, irrespective of the [CO32−]. Both O. universa and G. sacculifer exhibited reduced final shell weight and calcification rate under low [CO32−]. For the [CO32−] expected at the end of the century, the calcification rates of these two species are projected to be 6 to 13% lower than the present conditions, while the final shell weights are reduced by 20 to 27% for O. universa and by 4 to 6% for G. sacculifer. These results indicate that ocean acidification would impact on calcite production by foraminifera and may decrease the calcite flux contribution from these organisms.